Men with low IQs are more likely to attempt suicide, a Swedish study found, in what is the first association between intellectual performance and suicide.

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The study was based on an analysis of some 1.1 million Swedish men whose intelligence quotients (IQ) were measured during conscription tests, at around the age of 18, and who were followed for an average of 24 years.

When adjusting for age, the study published in the British Medical Journal found men with the lowest IQs were almost nine times as likely to be admitted to hospital for attempted suicide than men in the highest IQ groups.

"What we found is, we can say, the first association between intellectual performance and suicide," Finn Rasmussen of Stockholm's Karolinska institute told AFP.

"That means that the higher the intelligence, the lower the risk of attempting suicide."

Rasmussen cautioned that the study did not follow women, and that the inverse association between IQ and risk of attempted suicide did not hold for people who had mental illnesses such as severe depression or schizophrenia.

But he indicated his team believed the results of the study, although it followed only Swedish men, "could be generalised internationally, at least to the westernised societies."

Although Rasmussen said the study did not offer any short term solutions for significantly improving suicide prevention, it might be of "some interest (for doctors) to keep in mind that the risk (of attempting suicide) is higher among the people who have lower intelligence."

The study was carried out in collaboration with British and Australian researchers.